1. Field
The present disclosure relates to a lithium secondary battery.
2. Description of the Related Art
Silicon has been studied for use as a negative electrode material for lithium ion batteries since silicon has a high theoretical capacity of 4200 milliampere-hours per gram (mAh/g) and a low cost. However, silicon undergoes a volume expansion when alloyed with lithium during discharge of a battery to form Li4.4Si and thus the silicon active material becomes electrically isolated in the electrode and the electrolyte decomposition reaction increases according to the increase in the specific surface area of the silicon. To address these problems, a structure that reduces the volume expansion of the silicon so that it undergoes less pulverization has been developed or alternatively formation of a coating layer of carbon or the like on a surface of the silicon has been suggested. However, general silicon materials do not exhibit satisfactory volume expansion reduction effects or battery charging/discharging efficiency. There remains a need for improved lithium secondary battery materials.